Bronchoscopy in the emergency department.

BACKGROUND: Flexible bronchoscopy has been safely used for decades in ambulatory and critical care settings to aid in the diagnosis and treatment of tracheobronchial tree disorders. Although emergency physicians have the requisite skills to operate and interpret flexible bronchoscopy, no reports exist on the use of bronchoscopy by emergency physicians apart from endotracheal tube placement and confirmation. OBJECTIVE: The primary goal of this study was to describe the indications, outcomes and complications of flexible bronchoscopy performed by emergency physicians in an urban academic emergency department. METHODS: This was a single-center retrospective cohort study involving chart and video review of 146 patients over a 10.5-year study period. Patients of any age were included if they had been tracheally intubated or mechanically ventilated and underwent flexible bronchoscopy in the emergency department. After patients were identified, manual chart and video review was used to collect data on patient demographics, indications for intubation, indications for bronchoscopy, details of the bronchoscopy procedure, procedural findings, outcomes of the procedure, complications, provider training levels, and additional bronchoscopies performed after admission. The data was analyzed using descriptive statistics. RESULTS: 146 patients were included in the study and all bronchoscopies were performed or supervised by attending emergency physicians. After bronchoscopy, 24% of patients displayed improvement in oxygenation or lobar collapse while most patients had no change in clinical status. One patient had temporary hypoxemia after bronchoscopy. When another physician performed a subsequent bronchoscopy during admission, the findings were in agreement with the ED bronchoscopy 86% of the time. CONCLUSION: At our institution, emergency physicians can safely and effectively use flexible bronchoscopy to diagnose and treat critically ill patients.

Mouse Anesthesia: The Art and Science.

There is an art and science to performing mouse anesthesia, which is a significant component to animal research. Frequently, anesthesia is one vital step of many over the course of a research project spanning weeks, months, or beyond. It is critical to perform anesthesia according to the approved research protocol using appropriately handled and administered pharmaceutical-grade compounds whenever possible. Sufficient documentation of the anesthetic event and procedure should also be performed to meet the legal, ethical, and research reproducibility obligations. However, this regulatory and documentation process may lead to the use of a few possibly oversimplified anesthetic protocols used for mouse procedures and anesthesia. Although a frequently used anesthetic protocol may work perfectly for each mouse anesthetized, sometimes unexpected complications will arise, and quick adjustments to the anesthetic depth and support provided will be required. As an old saying goes, anesthesia is 99% boredom and 1% sheer terror. The purpose of this review article is to discuss the science of mouse anesthesia together with the art of applying these anesthetic techniques to provide readers with the knowledge needed for successful anesthetic procedures. The authors include experiences in mouse inhalant and injectable anesthesia, peri-anesthetic monitoring, specific procedures, and treating common complications. This article utilizes key points for easy access of important messages and authors' recommendation based on the authors' clinical experiences.

Effects of Standard and Sustained-release Buprenorphine on the Minimum Alveolar Concentration of Isoflurane in C57BL/6 Mice.

Both standard and sustained-release injectable formulations of buprenorphine (Bup and BupSR, respectively) are used as preemptive analgesics, potentially affecting gas anesthetic requirements. This study tested the effects of Bup and BupSR on isoflurane requirements and confirmed that buprenorphine could reduce isoflurane requirements during a laparotomy in mice. We hypothesized that both Bup and BupSR would significantly decrease the required minimum alveolar concentration (MAC) of isoflurane. C57BL/6 mice received either isotonic crystalloid fluid (control), Bup (0.1 mg/kg), or BupSR (1.2 mg/kg) subcutaneously 10 min prior to the induction of anesthesia. Each anesthetized mouse was tested at 2 isoflurane concentrations. A 300-g noxious stimulus was applied at each isoflurane concentration, alternating between hindfeet. In addition, a subset of mice underwent terminal laparotomy or 60 min of anesthesia after injection with Bup, BupSR, or saline to ensure an appropriate surgical plane of anesthesia. Mice were maintained at the lowest isoflurane concentration that resulted in 100% of mice at a surgical plane from the aforementioned MAC experiments (control, 2.0%; Bup and BupSR, 1.7%). Analysis showed that both Bup and BupSR significantly decreased isoflurane requirements by 25.5% and 14.4%, respectively. The isoflurane MAC for the control injection was 1.80% ± 0.09%; whereas Bup and BupSR decreased MAC to 1.34% ± 0.08% and 1.54% ± 0.09%, respectively. Sex was not a significantly different between the injection groups during MAC determination. All of the mice that underwent surgery achieved a surgical plane of anesthesia on the prescribed regimen and recovered normally after discontinuation of isoflurane. Lastly, heart and respiratory rates did not differ between mice that underwent surgery and those that were anesthetized only. Bup and BupSR are MAC-sparing in male and female C57BL/6 mice and can be used for effective multimodal anesthesia.

A Review of Strain and Sex Differences in Response to Pain and Analgesia in Mice.

Pain and its alleviation are currently a highly studied issue in human health. Research on pain and response to analgesia has evolved to include the effects of genetics, heritability, and sex as important components in both humans and animals. The laboratory mouse is the major animal studied in the field of pain and analgesia. Studying the inbred mouse to understand how genetic heritable traits and/or sex influence pain and analgesia has added valuable information to the complex nature of pain as a human disease. In the context of biomedical research, identifying pain and ensuring its control through analgesia in research animals remains one of the hallmark responsibilities of the research community. Advancements in both human and mouse genomic research shed light not only on the need to understand how both strain and sex affect the mouse pain response but also on how these research achievements can be used to improve the humane use of all research animal species. A better understanding of how strain and sex affect the response to pain may allow researchers to improve study design and thereby the reproducibility of animal research studies. The need to use both sexes, along with an improved understanding of how genetic heritability affects nociception and analgesic sensitivity, remains a key priority for pain researchers working with mice. This review summarizes the current literature on how strain and sex alter the response to pain and analgesia in the modern research mouse, and highlights the importance of both strain and sex selection in pain research.

West Nile virus: should pediatricians care?

Given the recurrent serious outbreaks of West Nile Virus (WNV) in the United States over the past decade, the spread to Canada and South America, the recurrent outbreaks in Europe, and the potential for serious neurological disease even in children under 18 years, paediatricians in affected areas must consider WNV in the differential diagnosis of all children presenting with aseptic meningitis, encephalitis and acute flaccid paralysis. Additionally, given that WNV encephalitis can occur after WNV infection, suspicion for neurological WNV disease must remain high even after otherwise benign febrile illnesses if the child lives in or has traveled to an affected region. Under-diagnosis in the pediatric population is likely a serious problem, necessitating further educational efforts. More follow-up studies of WNV neurological disease in children and youth are needed to better understand the potential long-term sequelae during vulnerable times of neurodevelopment and neural remodeling. Similarly, more research is need on short and long-term fetal outcomes of maternal WNV infection.

Severe enterovirus type 71 nervous system infections in children in the Shanghai region of China: clinical manifestations and implications for prevention and care.

BACKGROUND: Severe outbreaks of enterovirus 71 (EV71) have been on the rise in the Western Pacific region, including in China since 2007. We describe features of pediatric patients admitted with severe disease EV71 to a tertiary care hospital during the 2010 ongoing outbreak in the Shanghai region. METHODS: The Shanghai EV71 outbreak was studied prospectively from January 2010 to December 2012. To be eligible, children had to be 1 month to <14 years of age, admitted with confirmed EV71 infection to Xinhua Hospital and have severe illness needing Pediatric Infectious Diseases Service care with symptoms/signs of high prolonged fever and/or very unwell general appearance and/or neurological findings but no underlying medical condition. Clinical, laboratory, treatment discharge and follow-up data were recorded and analyzed. RESULTS: Of 26, 829 children presenting with possible EV71 disease, 2.9% (767) were admitted, more from less developed areas than from Shanghai proper. Of these, 29.2% (224) had severe enough EV71 for study enrolment, 4 excluded for underlying disease. Of 220 enrolled, 40.5% (89) had neurological involvement, 10.5% (23) needed pediatric intensive care unit care and 3% (7) died. Factors associated with severe disease were young age, male gender, high white count, prolonged high fever, high glucose, high C-reactive protein and neurological findings. The majority with neurological involvement and all who died were from the countryside. Early intravenous gamma globulin intervention had better survival. No survivor had persistent sequelae 2 months after discharge. CONCLUSIONS: This study confirms the morbidity for EV71 disease in China, especially for patients from the countryside versus Shanghai proper. The potential impact of public education, an EV71 vaccine, and the potential benefits versus harms of IVIG treatment are discussed.

Particle retention in suspension-feeding fish after removal of filtration structures.

The suspension-feeding cichlids Oreochromis aureus (blue tilapia) and Oreochromis esculentus (ngege tilapia) are able to selectively retain small food particles. The gill rakers and microbranchiospines of these species have been assumed to function as filters. However, surgical removal of these oral structures, which also removed associated mucus, did not significantly affect the total number of 11-200 µm particles ingested by the fish. This result supports the hypothesis that the branchial arch surfaces themselves play an important role in crossflow filtration. Both species selectively retained microspheres greater than 50 µm with gill rakers and microbranchiospines intact as well as removed, demonstrating that neither these structures nor mucus are necessary for size selectivity to occur during biological crossflow filtration. After removal of the gill rakers and microbranchiospines, O. esculentus retained significantly more microspheres 51-70 µm in diameter and fewer 91-130 µm microspheres compared to retention with intact structures, but the particle size selectivity of O. aureus was not affected significantly. These results support conclusions from previous computational fluid dynamics simulations indicating that particle size can have marked effects on particle trajectory and retention inside the fish oropharyngeal cavity during crossflow filtration. The substantial inter-individual variability in particle retention by suspension-feeding fish is an unexplored area of research with the potential to increase our understanding of the factors influencing particle retention during biological filtration.

Building confidence in vaccines.

Despite significant efforts by governments, organizations and individuals to maintain public trust in vaccines, concerns persist and threaten to undermine the effectiveness of immunization programs. Vaccine advocates have traditionally focused on education based on evidence to address vaccine concerns and hesitancy. However, being informed of the facts about immunization does not always translate into support for immunization. While many are persuaded by scientific evidence, others are more influenced by cognitive shortcuts, beliefs, societal pressure and the media, with the latter group more likely to hesitate over immunization. Understanding evidence from the behaviour sciences opens new doors to better support individual decision-making about immunization. Drawing on heuristics, this overview explores how individuals find, process and utilize vaccine information and the role health care professionals and society can play in vaccine decision-making. Traditional, evidence-based approaches aimed at staunching the erosion of public confidence in vaccines are proving inadequate and expensive. Enhancing public confidence in vaccines will be complex, necessitating a much wider range of strategies than currently used. Success will require a shift in how the public, health care professionals and media are informed and educated about vaccine benefits, risks and safety; considerable introspection and change in current academic and vaccine decision-making practices; development of proactive strategies to broadly address current and potential future concerns, as well as targeted interventions such as programs to address pain with immunization. This overview outlines ten such opportunities for change to improve vaccine confidence.

How to get and get rid of gonorrhea.

Gonorrhea remains as a significant public health concern with an estimated 88 million new cases per year globally. Gonorrhea is a disease of sexual networks and is most prevalent in youth, men who have sex with men, and the socioeconomically disadvantaged. Highly adaptive through years of co-evolution, gonorrhea has developed multiple ways of evading the human immune system. Although new molecular-based strategies have opened avenues for less invasive testing, education and accessibility issues persist. Novel strategies, including use of the internet and social media, are required to better target high risk groups for education, testing, and treatment. Increasing the availability of youth-friendly health services will also help foster earlier gonorrhea diagnosis and management. The inappropriate and overuse of antibiotics and propensity of gonococcus for mutation has led to growing microbe resistance. Treatment failures now include both oral and intravenous formulations of third generation cephalosporins; key front line recommended gonococcal treatment in many countries. With treatment options dwindling, the need for better preventative strategies has never been more important. This overview highlights some of the major aspects of gonococcal infection, including the epidemiology of the disease with an emphasis on sexual networks, new diagnostic techniques, treatment options in the face of evolving gonococcal resistance, and notes potential new preventative strategies.

Age-related changes in core body temperature and activity in triple-transgenic Alzheimer's disease (3xTgAD) mice.

Alzheimer's disease (AD) is characterised, not only by cognitive deficits and neuropathological changes, but also by several non-cognitive behavioural symptoms that can lead to a poorer quality of life. Circadian disturbances in core body temperature and physical activity are reported in AD patients, although the cause and consequences of these changes are unknown. We therefore characterised circadian patterns of body temperature and activity in male triple transgenic AD mice (3xTgAD) and non-transgenic (Non-Tg) control mice by remote radiotelemetry. At 4 months of age, daily temperature rhythms were phase advanced and by 6 months of age an increase in mean core body temperature and amplitude of temperature rhythms were observed in 3xTgAD mice. No differences in daily activity rhythms were seen in 4- to 9-month-old 3xTgAD mice, but by 10 months of age an increase in mean daily activity and the amplitude of activity profiles for 3xTgAD mice were detected. At all ages (4-10 months), 3xTgAD mice exhibited greater food intake compared with Non-Tg mice. The changes in temperature did not appear to be solely due to increased food intake and were not cyclooxygenase dependent because the temperature rise was not abolished by chronic ibuprofen treatment. No ß-amyloid (Aß) plaques or neurofibrillary tangles were noted in the hypothalamus of 3xTgAD mice, a key area involved in temperature regulation, although these pathological features were observed in the hippocampus and amygdala of 3xTgAD mice from 10 months of age. These data demonstrate age-dependent changes in core body temperature and activity in 3xTgAD mice that are present before significant AD-related neuropathology and are analogous to those observed in AD patients. The 3xTgAD mouse might therefore be an appropriate model for studying the underlying mechanisms involved in non-cognitive behavioural changes in AD.

A five-year review of Pseudomonas aeruginosa bacteremia in children hospitalized at a single center in southern China.

BACKGROUND: Pediatric Pseudomonas aeruginosa bacteremia is uncommon. It is mostly seen with impaired immune defenses and is most often nosocomially acquired, but it does occasionally occur in the previously healthy. Empiric antibiotics not effective against P. aeruginosa can result in poor outcomes. To determine the risk factors for P. aeruginosa bacteremia, all pediatric cases of P. aeruginosa bacteremia hospitalized at a single center over a 5-year period were reviewed. METHODS: A retrospective cohort study (2006-2010) of P. aeruginosa bacteremia in children under 14 years of age assessing demographics, the presence of underlying diseases, whether nosocomially acquired, clinical and laboratory findings, P. aeruginosa antibiotic susceptibility, antibiotic therapy, and clinical outcomes was performed. RESULTS: Thirty-one children, mean age 46 months, had P. aeruginosa bacteremia (2.6% positive blood cultures); 18 cases were nosocomial, none were multi-resistant, and 13 (42%) had P. aeruginosa isolated from a site other than blood. Ten cases occurred in previously healthy children, all of which were community-acquired, and these children were more likely to present with seizures and gastrointestinal findings than those with underlying conditions. The overall case fatality rate was 52% (16/31); 6/16 were previously healthy. Fatal cases had more leukopenia, elevated aspartate aminotransferase, and lower prealbumin A. Fewer fatal cases (6/16 vs. 14/15) had initial antibiotic coverage effective for P. aeruginosa (p=0.002). No difference in case fatality rate (p>0.05) or antibiotic sensitivity (p>0.05) was found between community-acquired and nosocomial cases. CONCLUSIONS: P. aeruginosa bacteremia in children is rare but often fatal if initial antibiotics do not cover P. aeruginosa. Factors indicative of P. aeruginosa bacteremia remain elusive, especially in previously healthy young children. However, P. aeruginosa bacteremia should be considered if children present with a grave illness, seizures, serious gastrointestinal findings, hypotension, and leukopenia.

Beta-2-transferrin to detect cerebrospinal fluid pleural effusion: a case report.

INTRODUCTION: Pleural effusion secondary to ventriculoperitoneal shunt insertion is a rare and potentially life-threatening occurrence. CASE PRESENTATION: We describe a 14-month-old Caucasian boy who had a ventriculoperitoneal shunt inserted for progressive hydrocephalus of unknown etiology. Two and a half months post-shunt insertion, the patient presented with mild respiratory distress. A chest radiograph revealed a large right pleural effusion and a shunt series demonstrated an appropriately placed distal catheter tip. A subsequent abdominal ultrasound revealed marked ascites. Fluid drained via tube thoracostomy was sent for beta-2-transferrin electrophoresis. A positive test was highly suggestive of cerebral spinal fluid hydrothorax. Post-externalization of the ventriculoperitoneal shunt, the ascites and pleural effusion resolved. CONCLUSION: Testing for beta-2-transferrin protein in pleural fluid may serve as a useful technique for diagnosing cerebrospinal fluid hydrothorax in patients with ventriculoperitoneal shunts.

Self-assembled monolayers of alkanethiols on InAs.

We describe the deposition and properties of self-assembled monolayers (SAMs) of methyl-terminated alkanethiols on InAs(001) surface. For these model hydrophobic films, we used water contact angle measurements to survey the preparation of alkanethiol monolayers from base-activated ethanolic solutions as a function of the solution and deposition parameters, including chain length of alkanethiols, deposition time, and solution temperature and pH. We then used X-ray photoelectron spectroscopy (XPS), ellipsometry, and electrochemistry to characterize the composition and structure of octadecanethiol (ODT) monolayers deposited on InAs under optimized conditions. When applied to a thoroughly degreased InAs(001) wafer surface, the basic ODT solution removes the native oxide without excessively etching the underlying InAs(001) substrate. The resulting film contains approximately one monolayer of ODT molecules, attached to the InAs surface almost exclusively via thiolate bonds to In atoms, with organic chains extended away from the surface. These ODT monolayers are stable against degradation and oxidation in air, organic solvents, and aqueous buffers. The same base-activated ODT treatment can also be used to passivate exposed InAs/AlSb quantum well (QW) devices, preserving the unique electronic properties of InAs surfaces and allowing the operation of such passivated devices as continuous flow pH-sensors.

Project integrate: translating screening and brief interventions for alcohol problems to a community hospital emergency department.

Screening and brief intervention (SBI) for alcohol problems in the emergency department (ED) is effective. The objective of this study was to examine the translation of SBI into a busy community ED environment. The authors assessed key stakeholders views of SBI delivery model, then utilized feedback to adapt model. Adoption of SBI was recorded, with data collected on use of screening tool, and referral for a BI. Model was modified due to physicians' and nursing resistance; physicians only screened and a research assistant (RA) delivered the BI. When the RA was present, screening by ED staff increased from 50% to 71% but returned to 50% after the RA left. An identified opportunity was increased nursing interest after observation of SBI, with 15 nurses trained in SBI after ED intervention concluded. Important barriers to translating SBI to community ED clinical practice exist. However, with additional staff present, high levels of SBI can occur.

Intra-oral flow patterns and speeds in a suspension-feeding fish with gill rakers removed versus intact.

Oreochromis aureus, a species of tilapia, is a suspension-feeding fish that employs a pumping action to bring water into its mouth for filtering.To address questions about water flow inside the mouth, we used a microthermistor flow probe to determine the speed of intra-oral flow during suspension feeding in this species before and after surgical removal of gill rakers. Synchronization with high-speed external videotapes of the fish and high-speed video endoscopy inside the oropharyngeal cavity allowed the first correlation of oral actions with intra-oral flow patterns and speeds during feeding. This analysis established the occurrence of a brief reversal of flow ( approximately 80-ms duration) from posterior to anterior in the oropharyngeal cavity prior to every feeding pump (250-500-ms duration). In industrial crossflow filtration, oscillating or pulsatile flow increases filtration performance by enhancing the back-migration of particles from the region near the filter surface to the bulk flow region, thus reducing particle accumulation that can clog the filter. In endoscopic videotapes, these pre-pump reversals, as well as post-pump reversals ( approximately 500-ms duration), were observed to lift mucus and particles from the branchial arches for subsequent transport toward the esophagus. Intra-oral flow speeds were reduced markedly after removal of the gill rakers. We hypothesize that the decrease in crossflow speed during feeding pumps following the removal of gill rakers and mucus could be due to increased loss of water between the anterior branchial arches.

Mucus function and crossflow filtration in a fish with gill rakers removed versus intact.

Filtration mechanisms are known for only two species of suspension-feeding tilapia, each of which relies on a different method of particle retention. We used high-speed video endoscopy to assess whether a third species of tilapia, Oreochromis aureus, with gill rakers intact as well as surgically removed, uses mucus in the oropharyngeal cavity for hydrosol filtration or uses crossflow filtration to retain particles during suspension feeding. Although a large amount of mucus was visible during feeding with rakers intact, particles were rarely retained in the mucus. The hypothesis that the presence of mucus results in particle entrapment by hydrosol filtration is rejected for O. aureus. Rather than functioning as a sticky filter, mucus is proposed to function in this species to regulate the loss of water between the rakers and between the anterior branchial arches, increasing crossflow speed and thereby increasing the inertial lift force that transports particles radially away from the arches. Gill raker removal resulted in an almost complete lack of observable mucus in the oropharyngeal cavity, probably due to the removal of mucus-secreting cells attached to the gill rakers. However, endoscopic videotapes showed that crossflow filtration continued to operate in the absence of gill rakers and mucus, indicating that the surfaces of the branchial arches play an important role in crossflow filtration.

Self-identification as "down low" among men who have sex with men (MSM) from 12 US cities.

Men who have sex with men (MSM) who are on the "down low" (DL) have been the subject of considerable media attention, but few data on this population exist. This exploratory study (N=455) compared MSM who considered themselves to be on the DL with MSM who did not (non-DL MSM). 20% self-identified as DL. Blacks and Hispanics were more likely than Whites to self identify as DL. MSM who did not identify as gay were more likely than gay-identified MSM to describe themselves as DL. DL-identified MSM were less likely to have had seven or more male partners in the prior 30 days, but were more likely to have had a female sex partner and to have had unprotected vaginal sex. DL-identified MSM were less likely to have ever been tested for HIV than were non-DL MSM. Prevention agencies should expand existing programs for MSM to include specific efforts to reach DL MSM.

Endotracheal tubes versus laryngeal mask airways in rabbit inhalation anesthesia: ease of use and waste gas emissions.

In this study, we compared two endotracheal tubes (cuffed [Murphy Eye type] and uncuffed [Cole type]) and a pediatric laryngeal mask airway (LMA) with respect to their ease of use in rabbits and their capacities to limit waste isoflurane emissions. Animals (New Zealand White, 3.3 to 5.0 kg, n = 8) were sedated with intramuscular ketamine (50 mg/kg) and xylazine (10 mg/kg). After 5 min, the larynx was numbed with cetocaine, an intubation device was positioned, and anesthesia was maintained with isoflurane (2%) in oxygen (1 liter/min). Real-time atmospheric isoflurane emissions were assessed at the rabbit's oral commissure and in the operator's breathing zone (45 cm from the rabbit's nose) by using a portable infrared spectrophotometer. The LMA was placed more easily than was either endotracheal tube, especially by novices. The cuffed tube was positioned more readily than was the uncuffed variant. All three devices emitted isoflurane. The concentrations measured at the oral commissure for the LMA (mean +/- standard error, 8.4 +/- 0.6 ppm) were modestly higher than those acquired for the cuffed (6.7 +/- 0.5 ppm) and uncuffed (6.3 +/- 0.4 ppm) endotracheal tubes; the difference between the LMA and uncuffed tube was significant (P = 0.012). Isoflurane was not detected in the operator's breathing zone. These data show that the uncuffed endotracheal tube (usually used to anesthetize birds and reptiles) and the pediatric LMA can be used in rabbits as readily as a cuffed tube. In addition, our findings indicate that tradeoffs will be required in selecting a delivery system for this species, as the easiest apparatus (the LMA) also emits the most isoflurane waste.

Correlations among within-channel and between-channel auditory gap-detection thresholds in normal listeners.

We obtained data on within-channel and between-channel auditory temporal gap-detection acuity in the normal population. Ninety-five normal listeners were tested for gap-detection thresholds, for conditions in which the gap was bounded by spectrally identical, and by spectrally different, acoustic markers. Separate thresholds were obtained with the use of an adaptive tracking method, for gaps delimited by narrowband noise bursts centred on 1.0 kHz, noise bursts centred on 4.0 kHz, and for gaps bounded by a leading marker of 4.0 kHz noise and a trailing marker of 1.0 kHz noise. Gap thresholds were lowest for silent periods bounded by identical markers--'within-channel' stimuli. Gap thresholds were significantly longer for the between-channel stimulus--silent periods bounded by unidentical markers (p < 0.0001). Thresholds for the two within-channel tasks were highly correlated (R = 0.76). Thresholds for the between-channel stimulus were weakly correlated with thresholds for the within-channel stimuli (1.0 kHz, R = 0.39; and 4.0 kHz, R = 0.46). The relatively poor predictability of between-channel thresholds from the within-channel thresholds is new evidence on the separability of the mechanisms that mediate performance of the two tasks. The data confirm that the acuity difference for the tasks, which has previously been demonstrated in only small numbers of highly trained listeners, extends to a population of untrained listeners. The acuity of the between-channel mechanism may be relevant to the formation of voice-onset time-category boundaries in speech perception.

Isoflurane with morphine is a suitable anaesthetic regimen for embryo transfer in the production of transgenic rats.

During our initial attempts to produce transgenic rats, we found that an anaesthetic combination typically used for embryo transfer (intramuscular injection of ketamine [90 mg/kg] with xylazine [10 mg/kg]) yielded extensive variation in both the depth and length of anaesthesia. In the present prospective study, we compared the reproductive outcomes afforded by using either isoflurane (5% for induction, 2% for maintenance, carried in 2 l/min of oxygen) with morphine (5 mg/kg s.c., given immediately after isoflurane induction) or ketamine/xylazine in adult (250-300 g), pseudopregnant Sprague-Dawley rats. Each animal was anaesthetized with either isoflurane/morphine or ketamine/xylazine, after which 30 microinjected eggs were transferred into the left uterine horn. The mean pregnancy rate for isoflurane/morphine (15%) was 50% greater than that achieved with ketamine/xylazine (10%). The mean number of live pups (just over five per litter) was comparable for both regimens. All rats given isoflurane/morphine quickly achieved a surgical depth of anaesthesia and experienced a rapid postoperative recovery (3-5 min). In contrast, 25% of rats injected with ketamine/xylazine did not reach a depth of anaesthesia within 10 min that was sufficient for laparotomy, and all that were anaesthetized successfully required an extended postoperative recovery period (60-90 min). These data show that isoflurane/morphine is well tolerated by microinjected embryos and suggest that its use during embryo transfer may provide a means for both reducing the number of pseudopregnant females used and increasing the speed with which rat transgenic projects are completed.